Sintered titanium carbide bodies



United States Patent 3,510,276 SINTERED TITANIUM CARBIDE BODIES WaltherDawihl, Illingen, and Emil A. Klingler and Erhard Dorre, Plochingen,Germany, assignors t-o Feldmuhle Aktiengesellschaft, Dusseldorf, GermanyNo Drawing. Filed Mar. 20, 1969, Ser. No. 809,043 Claims priority,application Germany, Mar. 23, 1968, 1,758,043 Int. Cl. B22f 3/00, 3/10U.S. Cl. 29182.8 5 Claims ABSTRACT OF THE DISCLOSURE This inventionrelates to shaped bodies mainly consisting of titanium carbide andcontaining one or more metals of the iron group (iron, cobalt, nickel)for greater toughness.

Titanium carbide bodies of the composition described above are extremelyhard, and have been used successfully as tool bits on machine tools andin other applications in which high wear resistance is essential. Theiron metal component gives them not only toughness, but also goodresistance to thermal shock. Yet, the mechanical and thermal propertiesof the known titanium carbide bodies are still quite far from thosetheoretically expected from the constituents, and particularly themechanical strength is quite far below the theoretical optimum. It hasbeen impossible heretofore to produce shaped bodies consisting mainly oftitanium carbide which are truly dense. A porosity of ten percent oreven more is unavoidable.

It has now been found that the porosity of such titanium carbide bodiescan be reduced sharply, and the thermal and mechanical propertiesimproved correspondingly if the metallic phase contains titanium and/ orzirconium in an amount of ten to about ninety percent, all percentagevalues in this specification and the appended claims being by weightunless explicitly stated otherwise. Best results are achieved if thetitanium or zirconium content of the metallic phase amounts to to 40percent, the metal bound to the carbon in the non-metallic carbide phasebeing excluded from these percentage values and from the base ofcalculation to which they refer.

The titanium carbide bodies of the invention have a porosity of notsignificantly more, and usually less than five percent per volume, andthey make superior bearing sleeves or metal cutting tools because oftheir very low wear.

Further improvement can be had in the shaped bodies of this invention byadding one or more metals of Group 612 of the Periodic Table of Elements(chromium, molybdenum, and tungsten) to the metallic phase which amountsto about 10 to 30 percent of the shaped body. Significant eifects areachieved with as little as two percent of the Group 6b metal in themetallic phase, and not more than 50 percent thereof may be presentwithout again reducing the mechanical strength of the 'body. The metalsof Group 6b are particularly effective in improving impact and vibrationresistance.

The shaped bodies of the invention are prepared from a mixture of thecomponents in finely powdered form which is compacted in the presence ofa temporary binder,

whereupon the compact is sintered in a hydrogen atmosphere or in avacuum at a temperature above 1400 C. as is conventional in itself. Thetitanium or zirconium may be present initially as a powder of the metalor as the powdered hydride which is converted to the metal under thesintering conditions. The sintering conditions can usually be controlledmore easily by first preparing an alloy of the metallic ingredients andmixing the powdered alloy with the non-metallic carbide prior tocompacting and sintering.

Under some conditions, however, shaped bodies of highest density areachieved when the initial mixture contains the individual components asseparate particles, and an alloy of the iron group metal or metals withthe titanium or zirconium is formed only during sintering. It has beenfound that under these conditions the metallic phase is enriched withtitanium or zirconium near the interface with the non-metallic carbidephase.

The following examples are further illustrative of this invention, butit will be understood that it is not limited to the examples.

EXAMPLE 1 Finely ground titanium carbide was mixed with a powdered alloyof titanium, cobalt, iron, and chromium to make the overall compositionof the mixture TiC, 8% Ti, 5% Co, 1% Fe, and 1% Cr. A small amount of anorganic binder was added, the mixture was compacted in the usual manner,and the green compact was sintered for 60 minutes in a hydrogenatmosphere at 1550 C.

The thermal and mechanical properties of the shaped body so obtainedwere substantially superior to the corresponding properties of controlsfrom whose composition the titanium had been omitted. Omission of thechromium resulted in a smaller, but significant loss in quality.

EXAMPLE 2 Powdered ingredients were employed in preparing a mixtureconsisting of 70% titanium carbide, 5% tungsten carbide, 10% molybdenum,10% nickel, and 5% titanium hydride. The mixture was converted to agreen compact as described in Example 1, and the compact was sintered at1500 C. for 30 minutes.

It was superior in its properties to conventionally prepared controlsnot containing titanium and/or molyb denum.

EXAMPLE 3 The method of Examples 1 and 2 was employed in making shapedbodies of the invention from starting materials having the followingcompositions:

The mechanical and thermal properties of the resulting sintered materialcompared favorably with those of otherwise similar materials lackingtitanium or zirconium as an essential ingredient.

What is claimed is:

1. A shaped body comprising 10 to 30 percent of a metallic component,the remainder of said body consisting essentially of titanium carbideuniformly mixed with said metallic component, said metallic componentincluding 10 to about ninety percent titanium or zirconium, 0 to 50percent of at least one metal of Group 6b of the Periodic Table ofElements, the remainder of said metallic component consisting of atleast one metal having an atomic number between 26 and 28, saidlastmentioned metal being present in said metallic component in anamount of at least 10 percent.

2. A body as set forth in claim 1 having voids in an amount notsubstantially exceeding five percent per volume.

3. A body as set forth in claim 1, wherein metal of said Group 6b isprecent in an amount of at least 2 percent.

4. A body as set forth in claim 1, wherein said metallic component is analloy of said titanium or zirconium, said metal of Group 617, and ofsaid last-mentioned metal.

5. A body as set forth in claim 4, wherein said metallic componentcontains 10 to 40 percent titanium.

References Cited UNITED STATES PATENTS 10 CARL D. QUARFORTH, PrimaryExaminer A. J. STEINER, Assistant Examiner U.S. Cl. X.R.

